Fixed-polarity attachment-plug.



c. n. PLATTi l FIXED POLARITY ATTACHMENT PLUG.

, APPLICATION FILED APB.. 25,1910.

977,836., I- Patented Dec. 6,1910.

Il, 'n i @im mii ' /NVENTUR' I. l .LA y2 l TED sTATEs PATENT oEEic CLARENCE D., PLATT, or BmnGEPoaT, commcitlIcU'r.r

can not engage when reversed so that there can be no change in polarity, and the invenv tion has for its object tbsi-mplify,'cheapen and to generallyT` improve the constructlon and especially to provide a construction that will permit engagement of the contact pins with the base terminals even should the pins be appreciabl bent out of parallel, it being of course W'ellyunderstood that the plugs are subject -to hard usage and abuse and that the pins are very likely to get sprung, so that with bases provided with4 ordinar forms of terminals it is frequently quite di cult to effect an engagement of the pins with the'terminals wit-hout considerable'tentative bending or springingof `*the pins to make them engage.

With the aboveandjother objects/ in View the invention consists in certain details of.

construction which will be hereinafter described and then specifically pointed out in the claims hereunto appended.

part of this specification, Figure 1y is an elevation of my novel polarity attachment plug with the plug in engagement with the base;l Fig. 2 an elevation of the base with the plug removed Fig. 3 an elevation of the base with the cover plate removed;Fig. 4 a transverse section of the plug; Fig.'5 al detail View, on an enlarged scale,l illustrating the attachment of thevspring .to a contact bushing; Fig. 6 a section of the base on the line 6-6 in Fig. 3; Fig. 7 a section ofthe base on the line 7-7 in Fig.. 3; Fig. 8 alsection of the plug on a line at right angles to the section line of Fig. 4; and Fig. 9 is a section of one of the cover screws on an enlarged scale, showing the retaining collar.

20 denotes the base, 21 the cover plate and 22 the plug, all of which are made of insulating-material. The base is provided with sockets 23 suitably shaped to receive the ter- 4minals 24 loosely, with holes 25` through FIXED-Bonanni? ATTACHMENT-nire.

Specification oifxLetters Iatent. Application led April 25, 19'10.` Serial No. 657,558.'

'of Fairfield, State of' In the accompanying drawing forming a' untested nec.c,1o1o.

` which electrical conductors 4' (not lshown) pass and which lead into the sockets and with holes 27 for attaching screws (not shown). Each terminal comprises a plate bent to form lower and/upper steps, indicated respectively -by 28 and 29. The lower steps rest upon the bottoms fof the sockets v and the upper steps' upon shoulders 30 therein.

. 31 denotes tubular contact bushings which are adapted to 'receive contact pins 32v eX- tendmg from the plug and are provided with lsprings 33 having engaging projections 34 `whlch `are adapted to engage grooves-35 in the faces of the contact pms and to force the pins into close engagement with the walls of the bushings. The contact bushings and the springs are carried by the lower steps of the terminals and are attached thereto in the novel way which I will now describe. The lowerstep of, each terminal is provided with a hole 36. The lower end of the bushing is provided Witha reduced endl which passes 4through the hole leaving a shoulder 37 which engages the step and with slots 38 which are engaged by wings 39 on opposite sides vof the spring. The end of the bushing is lianged outward upon the under side of the step which rigidly locks the bushing and the spring to the step.

40 denotes a binding screw which engages the upper step of the bushing and to which an electrical conductor 26 attached. The

top of the base is preferably provided withval slight depression 41 whicli'receives the cover plate, which is secured in place by screws 42.

I preferably use screws having unthreadedV shanks,`indicated by 43, and rolled threads at their ends and retain the screws against .dropping outl when the cover plate is removed by means of collars 44 on the Shanks. These'collars are simply slipped over the thread and secured in place by flattening the collar against the shank. Suflicient space is left between thehead of the screw-and the collar to -permit the thread to be disengaged from the nut 45 inthe base without lifting the cover plate. When the cover plate is removed it can be handled freely without danger of losing the screws which are retained against detachment by the collars.

The plug is provided with a central hole 46^through whlch the conductors pass and with a recess 47 which receives the binding screws 48.

A novel feature of my present structure is that thc periphcries of the bases of thc contact pins are provided with bearing surfaces 49 and the binding screws are tapped into the pins at the bearing surfaces, thus dispensing with terminal plates for the binding screws Which require to be attached to theV plug by screws enteringv from the outer side. In the resent instance I have shown the bases o the contact ins' as considerably largerthan the operative portions and the bearing surfaces as lying at an. incline to the axes of the pins. .These details of construction, however, are not of the essence of the invention, it being simply required that the bases of the contact pins be large enough to permit the binding screws to be tapped into th'em and` to provide bearing surfaces between which and the heads of the screws the wires may be clamped in the usual manner. The bases of the contact ins are rigidly secured to the plug by molding them into the material thereof.

In order to permanently fix the polarity of the plug, the contact pins are provided with a flat side, as at- 50, the grooves 35 for engagement with the projections on the springs being on the at sides, and the holes 51 in the cover plate through which the contact pins are passedare made part round with a straight side, so that the pins can only enter said holes when in proper relation as to polarity with the terminals and cannot be forced into said holes when reversed. The holes 21 are, however, necessarily slightly larger than the contact pins. The terminals are simply retained in place by the cover plate but have considerable freedom of movement in the sockets. This is an important feature of the invention as it enables engagement of the contact pins with the contact bushings to be made even when the contact pins are fs rung appreciably out of arallel the terminals shifting in their soc etsv sufficiently to adapt themselves to the alinement of the contact pins and the springs forcing the pins into contact with a large portion of the lbushings under all circumstances, so that perfect electrical con nection is assured.

Having thus described my invention I claim: l l

1. A fixed polarity attachment plug comprising a base, terminals carried thereby, a

cover plate with part round holes having a straight side and a plug having part round contact'pins with a flat side corres onding with the straight side of a hole in te cover plate.

plate and attaching 2. Axed polarity attachment plug comprising a base havin sockets, loose terminals therein, a cover p ate having part round holes with a straight sideand a lug having part round contact pins with a at side corresponding with the straight side of a hole in the cover plate.

3. A fixed polarity attachment plug com` prising a base having sockets with a shoulder, loose terminals therein each comprisino` a lower step carrying .a contact bushing and an upper step engaging a shoulder and carrying a binding screw, a cover plate having part round holes with a straight side,

and a plug having part'round contact pins with a flat side corresponding with the straight side of a hole in the cover plate.

4. lA fixed polarity attachment plug comprising a base having sockets, loose terminals therein each comprising a contact bushin with a spring having a projection, and a binding screw, acover plate having part round ho es with a straight side, and a plug having part round contact pins with a flat side corres onding with the straight side of a hole in t e cover late.

5. A terminal o the character described comprising a plate bent to form upper and lower steps, said lower step having a hole, a

contact bushing having a reduced'end leaving a shoulder and slots and a spring within the bushing having win s engaging the slots, the reduced end of t e bushing being flanged outward under the ste whereby the spring and bushing are locke to the plate.

6. plug of the character described comprising a body havino' contact pins molded therein each provided with a base the periphery of each base being provided with flattened ing screws arranged to coperate with said iattenedf portions to clamp conductor wires to said plugs.

7. The combination with a base, of a cover screws having unthreaded Shanks with col ars secured to the Shanks so that the screws may be detached from the base without raising the cover plate and detachment of the screws from the cover plate is prevented. In testimony whereof I affix my signature in presence of two witnesses.

p CLARENCE D. PLATT.

hWitnesses:

A. M. Woos'rnn,

S. W. ATHERfroN.

ortions arranged at an incline with relation to the axis thereof, and bind- 

